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a COLORADO <br />Division of Reclamation, <br />Mining and. Safety <br />Department of Natural Resources <br />1313 Sherman Street, Room 215 <br />Denver, CO 80203 <br />MEMORANDUM <br />. To: Michael Cunningham <br />From: Tim Cazier, P.E. <br />Date: March 6, 2015 <br />Re: Ralston Quarry — Permit No. M- 1974 -086 / AM -03 <br />Stability Analysis, Preliminary Adequacy Review <br />The Division of Reclamation, Mining and Safety engineering staff (Division) has reviewed the <br />Geotechnical Stability Exhibit, dated November 2014 and a supplemental February 2015 <br />geotechnical stability exhibit included in the Amendment 3 (AM -3) application with summaries <br />prepared by Greg Lewicki And'Associates, and analyses discussed by Brierley Associates (dated <br />July 22, 2014 and February 10, 2015, respectively). <br />The review consisted of comparing the application content with specific requirements of Rule <br />6.5 of the Minerals Rules and Regulations of the Colorado Mined Land Reclamation Board for <br />the Extraction of Construction Materials. Comments are identified below along with suggested <br />actions to correct them. <br />Brierley Associates Comments <br />1. July 22, 2014 Letter, Section 1.2 — This could be just a matter of semantics, but the text: <br />` Brierley analyzed three - dimensional wedge failures that could occur based on various <br />slope configurations to achieve a minimum allowable FOS of 1.3 for wedge stability" <br />implies analyses were evaluated until the minimum FOS was achieved as opposed to <br />evaluating multiple slope configurations to ensure the lowest FOS was at least 1.3. <br />Please confirm that no proposed final slope configurations were analyzed that resulted in <br />a FOS less than 1.3. <br />2. July 22, 2014 Letter, Section 1.4 — Map C -4 created by Greg Lewicki And Associates <br />indicates there will be a north dipping bench (south highwall of the pit, Section B -B'). <br />coo <br />1313 Sherman Street, Room 215, Denver, CO 80203 P 303.866.3567 F 303.832.8106 http: / /mining.state.co.us �e �90� <br />I * <br />John W. Hickenlooper, Governor I Mike King, Executive Director I Virginia Brannon, Director * * • <br />* 1876 �` <br />